1CVM 6101Radiographic Anatomy of the ThoraxTravis Saveraid, DVM, DACVRDept. of Medical ImagingCollege of Veterinary MedicineUniversity of MinnesotaVeterinary Medical CenterUNIVERSITY OF MINNESOTACVM 6101 [Imaging Anatomy]• Goals & Expectations:– Identify specific structures or parts thereof– Understand why the views (projections) look as they do– Keep in mind that the items listed in the “to know” lists are from the perspective of practicing radiologists– If asked, be able to describe what soft-tissue (muscle, tendon, ligament, vessel, or alimentary/parenchymal) structure(s) attach to, pass through, or lie in contact with a given anatomic landmark or regionVeterinary Medical CenterUNIVERSITY OF MINNESOTAA new way to look at your pets• 3D to superimposed 2D• Color to shades of GRAY• Challenging?2Yes• Thoracic radiographic interpretation is consistently difficult for students AND veterinarians.• Tremendous variation in normal – small dogs, short dogs, fat dogs, tall dogs, skinny dogs• Even in the same patient – inspiration, expiration, right lateral recumbence, left lateral recumbenceNormal Thorax - LateralNormal Thorax –Ventral DorsalVD3Normal ThoraxVDNormal ThoraxVDNormal Cat4Normal CatNormal Lateral View: inspiration/expirationNormal Ventrodorsal View: inspiration/expiration5To Know List• 1) heart, left atrial region• 2) heart, left ventricular region• 3) heart, right atrial/aortic root/pulmonary trunk region• 4) heart, right ventricular region• 5) caudal vena cava• 6) lobar pulmonary arteries• 7) lobar pulmonary veins• 8) approximatelung lobe location [cranial, middle, caudal, accessory]• 9) left and right diaphragmatic crura• 10) diaphragmatic cupola• 11) costochondral junctions, bodies, and costal cartilages of the ribs• 12) manubrium sterni• 13) xiphoid of the sternum• 14) trachea• 15) mainstem bronchi• 16) aorta• 17) approximatearea of the cranial vena cava• 18) larynx• 19) understand the “potential space” concept of and know the contents of:• - pleural space• - mediastinumInterpretive Background: THORAX• Heart and VesselsVeterinary Medical CenterUNIVERSITY OF MINNESOTAHeart – Lateral Perspective6Cardiac Margins - Clock Face Diagram [lateral view]Cardiac Perspective Lateral Thoracic ViewAortaVena CavaCaudalTracheaHEART12:003:006:009:00Cranial Cardiac Waist:Aorta, Rt. Atrium, Pulmonary TrunkCaudal Cardiac Waist:Lt. AtriumRight VentricleLeft VentricleLateral HeartSagittal plane thoracic CT7Heart – Ventral Dorsal PerspectiveCardiac Margins – VD clock face Cardiac Perspective Ventrodorsal Thoracic ViewR L12:003:006:009:00Main Pulmonary TrunkAorta (hidden in mediastinum)Left AuricleLeft VentricleRight VentricleRight AtriumHEARTHeart – VD PerspectiveR121RVLVLV wallAortaMPALVRA8Heart – Ventral Dorsal PerspectiveInterpretive Background: THORAX• Thoracic Circulatory Pattern:cranial/caudal* vena cavaÆright atrium*Ætricuspid valveÆright ventricle*Æ pulmomary trunk*Ælobar pulmonary arteries*Ælobar pulmonary veins*Æleft atrium*Æmitral valueÆleft ventricle*Æaorta*• * sufficiently visible to be survey radiographically usefulVeterinary Medical CenterUNIVERSITY OF MINNESOTAInterpretive Background: THORAX• Intrapulmonary Circulatory Pattern:– ARTERY/BRONCHUS/VEIN TRIAD(one in each major lung lobe) – USED AS INDIRECT INDICATOR OF LEFT HEART FUNCTION• lobar pulmonary arteries– Dorsal to veins on lateral views– Lateral to veins on VD/DV Views• lobar pulmonary veins– Ventral to veins on lateral views– Medial to veins on VD/DV ViewsVeterinary Medical CenterUNIVERSITY OF MINNESOTA9Veins are VentralVeins are Central• On the lateral radiograph, the CRANIAL lobar pulmonary veins are ventral to the artery, bronchus.• On the VD/DV radiographs, the CAUDAL lobar pulmonary veins are central to the artery, bronchusLung Vessel Diagram [lateral view]Lobar Pulmonary Vessels (left lateral view)arteryveinbronchusNormal Thorax - Lateral10Normal Thorax –Ventral DorsalVDNormal Cranial Vena (CrVC) Cavogram (dog)CrVCCaudal Vena Cava (CaVC)RCT Venocavagram11Interpretive Background: THORAX• AirwaysVeterinary Medical CenterUNIVERSITY OF MINNESOTAInterpretive Background: THORAX• Upper Airways (extrapulmonary):nasal passages, pharynx. larynx • Lower Airways (extrapulmonary): extrathoracic tracheaintrathoracic tracheaproximal mainstem bronchi• Intrapulmonary Airways: distal mainstem bronchi Æ bronchioles[airways distal to 3rdorder bronchi notnormally visible]Veterinary Medical CenterUNIVERSITY OF MINNESOTANormal Larynx/Pharynx12Interpretive Background: THORAX• LungsVeterinary Medical CenterUNIVERSITY OF MINNESOTANormal Dog Lateral ViewInterpretive Background: THORAX• Left Lobes (radiologist’s functional perspective):cranial portion of left cranial (left cranial)caudal portion of left cranial (left middle)left caudal (left caudal)• Right Lobes: right cranialright middleright caudalaccessoryVeterinary Medical CenterUNIVERSITY OF MINNESOTA13Lung Diagram [lateral view]Lung Diagram [VD view]Diagram: Airway Subdivisions[dog & cat]14Barium aspiration outlining airwaysCVM 6101 [Imaging Anatomy]• Diaphragm: Broad Anatomic Regions– R and L crura– Cupola (dome)Veterinary Medical CenterUNIVERSITY OF MINNESOTACVM 6101 [Imaging Anatomy]• Diaphragm:–VÆD/DÆV and RÆL/LÆR views– Beware of superimposed structures including vertebrae, ribs, sternebrae, lungs, stomach, nipples, fascial planes, trachea, etc.– Remember, the diaphragm is a sling-like muscle that “actively” contracts (caudally) and “passively” relaxes (cranially) [numerous influences such as lungs, abdominal fat, etc.]Veterinary Medical CenterUNIVERSITY OF MINNESOTA15CVM 6101 [Imaging Anatomy]• Diaphragm:– Appearance changes depending on DV vs. VD views (with the X-ray beam is centered on the heart): • On DV views, the diaphragm usually has one broad dome which corresponds to the cupola• On VD views, the diaphragm usually has “3 humps”corresponding to the two crura and the central cupola• Appearance related to beam divergence and diaphragm orientation relative to the diverging beamVeterinary Medical CenterUNIVERSITY OF MINNESOTADiaphragm Appearance:VD vs. DV (From Grandage)Normal Dog ThoraxVD/DV16Normal Dog ThoraxVD/DVCVM 6101 [Imaging Anatomy]• Diaphragm:– Appearance changes depending on R vs. L recumbent lateral views (with the X-ray beam is centered on the heart): • On R lateral views,